Deformability evaluation of high-strength reinforced concrete columns

Plastic hinge length and ultimate curvature are the crucial parameters that enable inelastic deformability (deflection and rotation) of reinforced concrete columns to be evaluated. Prediction of deformability beyond the elastic range is important in the performance-based design of earthquake-resistant structures. Although large numbers of tests have been conducted in the past by numerous researchers on reinforced concrete columns subjected to simultaneous axial load and large inelastic displacement, available design tools that enable rapid evaluation of deformability of reinforced concrete columns are still limited. The situation is even worse for high-strength reinforced concrete columns. The objective of this paper is to investigate plastic hinge length and ultimate curvature for deformability evaluation of high-strength reinforced concrete columns. In connection with this, two equations are proposed in this paper for estimating the plastic hinge length and ultimate curvature of high-strength reinforced concrete columns leading to their deformability evaluation. The proposed equations are used to evaluate the theoretical deflection of other researchers' column test specimens, and it is proven that these theoretical deflections mostly underestimate slightly their respective measured deflections. Therefore, the proposed equations can be used for conservative estimation of high-strength reinforced concrete column deformability at an early design stage without performing the tedious load–deflection analysis.